A facile one-pot synthesis of thiazo[2 ',3 ': 2,1] imidazo[4,5-b]pyrane; Thiazo[2 ',3 ': 2,1]imidazo [4,5,b]pyridine; Imidazo[2,1-b]thiazole and 2-(2-amino-4-methylthiazolo-5-yl)-1-bromo-1,2-ethanedione-1-arylhydrazines

Thiazole 1, when reacted with chloroacetyl chloride, afforded N-(5-acetyl-4 -methylthiazol-2-yl) chloroacetamide 2. It has been found that compound 2 r eacted with alpha-cyanocinnamonitrile derivatives 6a-c to afford reaction p roducts 8a-c. Also, compound 2 coupled smoothly with benzenediazonium chlor ide afforded the phenylhydrazone 14. Coupling of the sulfonium bromide 17 w ith diazotized aromatic amines or N-nitrosoacetanilides afforded the arylhy drazones 20a,b. Treatment of 16 with 2-cyanoethanethioamide afforded [4-(2- amino-4-methylfhiazol-5-yl) thiazol-2-yl] acetonitrile 22. (C) 2000 John Wi ley & Sons, Inc.